An optical parametrical oscillator of this kind is known from DE 42 19 169 A1.
Quite generally, tunable optical parametrical oscillators (OPOs) have been known for more than 25 years (J. A. Giordmaine, R. C. Miller, Phys. Rev. Lett. 14, 973 (1965). Reference is made also to U.S. Pat. Nos. 5,053,641 and 5,047,668 as regards the state of the art.
As far as tunable narrowband OPOs are concerned, reference is made to the publication by A. Fix, T. Schroder, R. Wallenstein, J. G. Haub, M. J. Johnson, B. J. Orr, JOSA B-10, 1744 (1993).
The above mentioned prior publication DE 42 19 169 A1 describes a laser arrangement for generating tunable narrowband coherent radiation, comprising first and second optical parametrical oscillators. In this case the spectral bandwidth of the original radiation of one of the two optical parametrical oscillators is reduced by a wavelength selective means and then introduced, as so-called injected stimulation radiation (seed radiation), into the other optical parametrical oscillator.
With this known laser arrangement, generation of the narrowband seed radiation and amplification of that radiation are accomplished in two separate oscillators. As a consequence, different subassemblies must be set in synchronysm when wavelength tuning is effected.
A Raman oscillator with which pumping radiation is divided into two partial beams by a beam splitter is described in U.S. Pat. No. 4,575,645. This arrangement, however, does not comprise a wavelength selective means.
DE 41 38 843 A1 describes an optical parametrical oscillator wherein a pump beam and a signal beam impinge on the crystal to produce an idler beam and a signal beam, the energy of the pumping pulse largely being converted into the idler and signal beams mentioned.
U.S. Pat. No. 5,323,260 describes a delay means for pulse-shaped laser radiation.